Turbine-blade shrouding



A ril 19 1927.

p H. F. SCHMIDT- TURBINE BLADE SHROUDING Filed sept. 12.- 192s "hun Kga.

' inhmidt ENJENTOR WITNESSES:

ATTORNEY Cil Patented Apr. 19, 1927.

UNITED STATES PATENT QFFMJE..y

HENRY F. SCHMIDT, OF LANSDCVVN'E, PENNSYLVANIA, ASSIGNOR TO WES'IINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

TURBINE-BLADE srrnouioinu.

Application filed September My invention relates to elastic duid turbines, more particularly to the blading or Vbuckets thereof, and has for its object the provision of apparatus of the character designated which shall be sturdy of construction, simple and easy of manufacture and which shall render the turbine highly etlicient,

Apparatus embodying features of my invention is illustrated in the accompanying drawings forming a part of this specification wherein Fig. 1 is a fragmentary longitudinal sectional view of a turbine having my invention applied thereto; Fig. 2 is a partial sectional view of the turbine rotor taken along the plane II-II of Fig. 1; Fig. 3 is a developed plan view of a partial row of buckets with the shrouding removed; and Iiig. 4L is a perspective v iew of my improved shrouding. f

As is Well known in the artto which my invention relates, a popular design of a relativ-ely small type of elastic fluid turliiue einbodies a rotor having open U-sliaped buckets milled or otherwise provided in the surface thereof. In operation, motive fluid is eX- panded through a suitable nozzle and is directed into the buckets for driving the rotor. 1While the construction described provides a, very sturdy structure which is remarkably free from difficulties in operation, steam or other motive fluid in its passage in .and out of the open buckets produces eddies in the flow that, lto a certain extent, minimize the efficiency of the turbine. It is also wellknownin the art that if a turbine blade or bucket can be so formed as to offer a tubular path for the motive fluid iow, eddies are avoided and the etticiency of the turbine is increased. It is accordingly the particular object of my invention to provide a bucket construction of the general character described wherein the motive fluid path therethrough is closed on its sides so as to be tubular in cross section and= eddics are avoided. y

In accordance with my invention I provide a shrouding, or cover, foi-open U-shaped turbine buck-ets in the form of a strip of metal having a series of inclined U-shaped projections or lugs thereon `which enter into the buckets the distances necessary to provide tubular passages through the buckets of the desired proportions for the motive iiuid. Preferably the shrouding is applied to buck- 12, 1925. Serial No. 56,016.

ets formed in the inner periphery of an over-l hangingflange of the rotor on account of ease of application and retention in place, though it will be apparent that it may be applied to open buckets formed in various ways in a rotor and also 'materially add to the eiiciency ofthe machine.

Referring now to the drawing for a better understanding of my invention, I show a turbine having a casing 10 and a rotor 1l,

mounted on a shaft 12. The rotor l1 is pro vided with an overhanging flange 13 in which is formed a series of buckets 14-14- The buckets 14-14 may readily be formed by milling into the material of the overhanging flange. Steam or other motive fluid is expanded through a suitable nozzle 16, directed into the buckets lil-14 and after performing useful work therein passes outwardly of the turbine casing through an exhaust opening 17. i

Referring to F 2 and 3 it may be seen that, Without some means for guiding the motive Huid in the buckets, eddies of flow are free to be set up therein. I accordingly provide `a shroudilig or cover S for the buckets which is so shaped as to form, with the buckets, a continuous tubular passage for the motive fluid passing therethrough which prevents the formation of eddies and permits the n'xaxinuun amount of energy to be abstracted from the motive fluid. Ref-ein ring to Fig. et it may be seen that the shrouding or cover 18 is comprised of a series of slanting til-shaped projections 19--19 overlapping each other so as to form a continu4 ous strip. In practice I forni this strip by drop forging the metal in a suitable die and bend it around in the form of a ring for covering the buckets milled into the inner periphery of the fiange 13. Upon insertion, the projections 19-19 lie within the open ends of the buckets and the outer surfaces of the projections, shown at @lf-2l in Fi 4, lie fiat against the tlat surfaces of the buckets as may be seen in Fig. i2. liVhere the buckets are milled on the inner surface of an overhanging flange of the rotor, centrifugal force in operation acts to hold the shrouding in close contact with the buckets. In such cases it is only necessary to secure the shrouding or cover 18 to a few points around the rotoi as at 9,2-22 in Fig. 2.

In order that the motive fluid path through the buckets formed by the projections 19`-l9 with'the buckets "may be of the proper proportions, it may beI necessary to cut away notches in the entrance edges of the blad'esas shown `lat 23-23 in Fig. 3. The f roundedends 'of the projections 19e-:19 'entei`- into the not-ches 23H23 in such a way that,

if desired, the motive fiuid passage through-'1 the bucket may be uniform throughout. rlhe size or proportions oit'theinotive fluid passage may otherwise be modified by varying` the width ofthe strip 18 in relation to the It will be apparent width of' the buckets.

"tliei"efore"'that by modifying the notch-es 235-28 and varying the widthof the strip 18 "andcontoiirof the projections 19-19, a tubu-l lar motive fluid path designed to` meet all practical conditions of motive iuid iiow may l be" designed.

From theforegoing it will be apparent that I'havedevised a shrouding for turbine buckets adapted to provide a motive fluid "path therethrough of the highest efficiency` which is'siinple of manufacture, sturdy of' `fcoiistriiction and easy of application. 25 f one form, it will be obvious to those 'skilled inthe artA that it is not so limited, but is` susceptible of various changes and modilk. l v l IVhile I have shown my invention in but fications', without departing troni the spirit thereof, and I desire, therefore, thatonly such limitations shall be placed thereupon as are imposed by' the prior art or as are specifically set forth in the appended claims.

Iliat I claim is:

1. In a turbine, the combination of a rotor having a series of `Ushaped buckets formed thereinand opening radially inwardly, and

a shrouding for said buckets comprising a strip of i'n'aterial with a series of' projections 'thereon fitting into the buckets and forming therewith a tubular U-shaped passage' for the motive fluid.

2. In a turbine, the combination of a rotor having a series of buckets formed around the periphery thereof and opening radially inwardly, and a shroud for said buckets comprising a strip of metal narrower than the buckets and havii'ig a series of U-'shaped projections thereon fitting into the open ends of the buckets forming therewith a tubular passage for the motive fluid.

3. In a turbine, thecombination of a rotor liaving an oveilianging iiange with a. series of buckets torlned in the inner'periphery` -thereof', and a shroud for said buckets coinprising a strip of' inetal having a series of U-shaped projections thereon fitting into the open ends of the buckets andtorining therewith a tubular passage for the motive fluid.

4. Iii-a turbine, thecombination of a rotor,

having an overhanging flange with a series of buckets formed in the inner periphery thereof', and a shroud for said buckets coinprisinga strip of metal `lia-ving a series of lslanting Uishaped projections lthereon fitting into the open ends of the buckets and extendiiiginwardly thereof forming 'a` closed Ulshaiped 'passage for 'the motive fluid.

5. In. a turbine, the combination of a rotor-having an overhanging flange with a series of buckets formed in the inner periphery thereof, and afshroud for said buckets comprising a strip of metal having a series of 'slaiiting U-shaped projections thereon fitting" into the open ends of the buckets and extending inwardly thereof forming a 'close'd U-shaped passage for the motive fluid and secured to the buckets in one or more places around the periphery of the rotor.

6. In a turbine, the combination of a rotor having an overlianging flangewith a series ofv buckets formed in the inner periphery thereof, and ashroud for said buckets comprising a circular strip of metal having a series of' U-sliaped projections thereon adapted to extend into the open ends lof the buckets formii'ig there-with Ia U-shaped passage' :tor the motive fluid and held in place mainly by centrifugal force.

. In a turbine, the combination of a rotoi having an overhanging flange with a series of buckets formed in the inner periphery thereof, anda shroud for jsaid buckets comprising a circular strip of metal narrower than the buckets andhaving a seiies iof' U- shaped projections thereon adapted to extend into the open ends of the buckets,- cui'ved slots'forined in the inlet edges of the buckets for the reception of the U- shaped projections, and means joining the circular strip to one or more buckets around the peripheryof the rotor.

8. In aturbine, the combination of a rotor having an overhanging fiange with arseri'es of buckets 'formed in the inner periphery thereof, a series of curved slots formed in the entrance edges of the buckets, and a 'sliroudiiig for the buckets comprising a strip of 'metal having a series of: curved projectioiis thereon fitting into the slotsand extending inwardly of the buckets forming a tubular curved passage for the motive fluid.

'i HENRY F. SCHMIDT. 

